How to Protect Your Plants from Frost

The cold can be a serious threat to plants; even to evergreens which are more acclimatised to winter conditions. How does frost cause damage to plants? In tender varieties, the water in the cells freezes, causing damage to the cell walls that result in limp, brown plants. In hardier plants, although the cells are less vulnerable, the soil can freeze, preventing the plant from getting the all-important moisture it needs to survive.

We think these are three of the best ways of protecting your garden plants in winter.

How to protect your plants from frost

1. Plant strategically

When considering how to protect your plants from frost, the most effective method is to plant strategically.

Areas that are afforded a greater level of protection – sheltered by a wall or by larger, more established hedges for example – should be reserved for the more delicate plants.

Frost forms first in the lowest areas of a garden, so if you have a significant hollow or dip, save this for the hardier plant varieties.

For very delicate plants, defrosting too quickly after a cold night can cause greater damage than the initial freezing, so you should avoid planting them in east-facing areas that attract direct sunlight.

3. Apply a layer of mulch

Tender perennials can also be protected by applying a layer (around 5 cm) of mulch to keep the root systems warm. The mulch acts as an insulator, and prevents the soil from freezing.

Around the plants themselves, grit should be used between the mulch to allow greater drainage and prevent the roots rotting.

4. Cover delicate plants with a blanket

If a frost is predicted overnight, often covering more delicate plants with a blanket can be effective, although this does little to increase the temperature.

When covering plants, be careful not to let the blanket weigh down the branches or leaves; instead prop it up with stakes where necessary to prevent it from coming into direct contact with the plants.

Even larger and more hardy plants can benefit from some protection during the winter. Tree ferns for example should have their trunks wrapped – preferably with chicken wire and straw and not the traditional bubble wrap – in order to avoid rotting. The fronds can be left on over winter for added insulation, although they will most likely need to be removed in the spring.

5. Invest in a greenhouse or polytunnel

One of the most effective ways of protecting your garden plants in winter is by using a greenhouse.

If you’re looking to be able to control the growing environment of your plants to a higher degree, then a greenhouse or polytunnel is the answer. Polytunnels work in much the same way as greenhouses do – using solar radiation to trap heat within the structure – but they are a lot less expensive.

Greenhouses and polytunnels can extend a plant’s growing season or be used to recreate a growing climate that would not be achievable in your own garden. In addition to affording protection from wind and frost in winter, they also help maintain a constant temperature in summer.

Summary: how to protect your plants from frost

In general, golden or variegated varieties of plants are more vulnerable and less likely to make it through any cold winters.

Predictably, evergreens are a safe bet for any time of year, adding colour to the garden, but many varieties also make very effective wind shields for more delicate plants and can be used strategically. Hardy bulbs are those that tolerate, or even require, a period at cold temperature in order to produce the best flowers and some bulbs (best planted in spring) such as cyclamen coum, snowdrops and winter aconite flower throughout the winter, adding much needed colour.